Balanced slide-valve.



M. A. KNAPP BALANCED SLIDE VALVE.

APPLICATION FILED SEPT.29. 1914.

1,147,872. Patented July 27', 1915, 2 sums-sum 1.

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BALANCED. SLIDE VALVE.

APPLICATION FILED SEPT-29. 19M.

1,147,872. I Patented July 27, 1915.

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MERRITT A. KNAPPQ OF ROSALIA, WASHINGTON.

, BALANCED SLIDE-VALVE.

. To all whom it may concern Be it known that I, Mnnnrrr A. KNAPP, acitizen of the United States, residing at Rosalia, in the county ofWhitman and State of 1V ashington, have invented certain new and usefulImprovements in Balanced SlideValves, of which the following is aspecification. v

This invention relates to that class of balanced valves in whichpressure within the steam chest is utilized for thrust of the slidevalve upon its seat and against a balancing piston to relieve pressureof the valve upon its seat, the relative areas of the valve and pistonbeing such as to provide suflicient preponderance of pressure on thevalve to hold the same lightly in working engagement on its seat.Heretofore in constructions of this character, reliance has been placedupon exhaust steam on the opposite end of the piston to overcome anytendency of the piston to unduly rise and unseat the valve.

The novel feature of this invention consists in providing means forexerting ace-nstant thrust on the balancing piston to seat the valve,such means being adjustable so as to permit of the exertion of anydesired degree of seating pressure.

Other features and objects of'the inven tion will be more fullydescribed in connec tion with the accompanying drawings, and will bemore particularly pointed out in and by the appended claims.

In the drawings: Figure 1 is a vertical sectional view ofan enginecylinder provided with my improved balance valve structure. Fig. 2 is asectional view on line 22 of Fig. 1. Fig. 3 is a perspective view of theslide valve and balancing piston, detached from the structure.

Like characters of reference designate similar parts throughout thedifferent figures of the drawings.

As illustrated, 1 designates an engine cylinder in which an enginepiston 2, is reciprocable. A piston rod 3 extends through a packinggland 4:, in the usual manner and a portion of the frame is indicated at5. The engine cylinder 1 is provided with a steam chest 6, and a valveseat 7, ports 8 being shown as leading from the steam chest to thecylinder. A slide valve is shown at 9, and is of the hollow type so asto establish communication between one of the ports 8 and the exhaustcavity 10. An exhaust pipe 11 Specification of Letters Patent.

. Patented July 27, 1915.

Application filed September 29, 1914. SerialNo. 864,078.

leads from the exhaust cavity 10. The slide valve 9 is provided with anattaching lug 12, which is bored, as at 13, to receive a valve rod 14:,the latter being shown as extending through a packing gland 15. Theinserted end of the rod 14 is secured in the bore 13 of the lug 12bymeans of nuts 16. Projecting upwardly from the lug 12 are ears 17between which is pivoted a connecting rod 18, as indicated at 19. Theupper end of the connecting rod 18 is pivoted at 20 to a balancingpiston 21. y

The steam chest .6 is provided with a removable cover 22, which is castintegral with a balancing cylinder 23 and the latter, is in free andconstant communication with the steam chest 6, at one end Of s-aidcylinder. The parts are so proportioned that the chest steam thrust face23, of-the piston 21, will be slightly reduced in. area with respect tothe upper face or area of the slide valve 9 so that there will be aslight preponderance of steam thrust pressure on the valve 9, over thatagainst piston 21 sothat during operation the valve 9 will be heldseated with a slight working pressure.

The upper end of cylinder 23 is provided with a removable head 24, and abearing bracket 25 is removably secured to said head by certain of thebolts 26 which anchor the head 24 to the cylinder 23. The bearingbracket 25 is provided with a bearing hub 27. Slidable in said hub 27,and through a packing gland 28, is a plunger rod 29, which extends intothe cylinder 23 for engagement against the upper or exhaust thrust face30, of the piston 21. A nut 31 is threaded on the plunger rod 29 and awasher 32 is disposed on said nut. Interposed between the washer 32 andthe bearing hub 27 is an expansively acting spring 33 which functions toforce the lower end of the rod 29 into constant pressure engagementagainst the exhaust thrust face 30 of the piston 21. By reason of thefact that the valve 9 reciprocates, a slight up and down movement willbe imparted to piston 21, however, throughout the movement of piston 21the pressure plunger 29 will exert a practically uniform pressurethereagainst in opposition to the steam chest thrust against the face23, of the piston 21. This yielding and constant pressure is in oneembodiment of the invention, a supplemental means for adding to thedownward pressure on piston 21 exerted by exhaust steam. However, in theevent that the designed preponderance of pressure on the slide valve 9is not sufi icient, and further, if under back pressure it Was necessaryfor the valve 9 to lift, the spring 33 would accommodate for either ofsuch actions or exigencies and thereafter automatically and quicklyrestore the parts to their normal Working position. Byreason of the nut31, the supplemental thrust of the plunger rod 29 may be varied in sucha manner that the very nicest and most accurate balance of the parts maybe obtained under Widely varying steam pressure.

A connection 34- delivers exhaust pressure from pipe 11 to an elongatedport 35, which opens into the cylinder 23 above the piston 21, althoughin some embodiments, this exhaust pressure may be omitted, and relianceplaced Wholly upon the adjustable pressure means.

It is believed that the utility and advan- H tages of my invention Willbe fully understood from the foregoing description, and

While I have herein shown and described one specific form of myinvention, I do not Wish to be limited thereto except for suchlimitations as the claims may import.

I claim 1. In an improved balanced slide valve structure,a steam chesthaving a slide valve seat and a balancing cylinder With one end of thelatter in constant free communication with said chest, a slide valvereciprocable on said seat, a balancing piston slidable in said cylinderand pivotally connected With said slide valve and under thrust of steamin said chest on one face of said piston to relieve pressure of saidvalve on its seat, a connection delivering exhaust steam from said chestto said cylinder for thrust on the remaining face of said piston topartially counter-act chest steam pressure, and adjustable springactuated means in constant pressure engagement with said piston duringmovement of the latter for supplementing the thrust of exhaust steam onthe exhaust face of said piston, substantially as de scribed.

2. In an improved balanced slide valve structure, a steam chest having aslide valve seat and 'a balancing cylinder With one end of the latter inconstant free communicationWith said chest, a slide valve reciprocableon said seat, a balancing piston slidable in said cylinder and pivotallyconnected With said. slide valve and under constant thrust of steam insaid chest on one face of said piston to relieve pressure of said valveon its seat, a connection delivering exhaust from said chest to saidcylinder for thrust on the remaining face of said piston to partiallycounter-act chest steam pressure, a plunger rod slidable in saidcylinder against the exhaust face of said piston, and a spring meansadjustably connected With said plunger and abutting said cylinder forholding said plunger in constant pressure engagement against said pistonto supplement the thrust of exhaust steam on the exhaust face of saidpiston, substantially as described.

3. In an improved balanced slide valve structure, a steam chest having aslide valve seat and balancing cylinder With one end of the latterinconstant free communication With said chest, a slide valvereciprocable on said seat, a balancing piston slidable in said cylinder,a piston rod having one endpivoted to said piston and its other endpivoted to said slide valve, one face of said piston being underconstant thrust from said steam chest and a connection deliveringexhaust steam to said cylinder for thrust on the remaining face of saidpiston to partially counter-act the thrust of the chest steam, a plungerrod slidable in said cylinder against the exhaust face of said piston,an adjustable nut on said plunger, and a spring interposed between saidnut and said cylinder for maintaining said rod in constant thrustengagement with said piston to supplement the thrust of said exhauststeam, substantially as described.

In testimony whereof I affix my signature in presence of two Witnesses.

MERRITT A. KNAPP.

V'Vitnesses r F. C. REED, J. W. BArLoRs.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents Washington, .D. C

